Golf is enjoyed by a wide variety of players—players of different genders, and players of dramatically different ages and skill levels. Golf is somewhat unique in the sporting world in that such diverse collections of players can play together in golf outings or events, even in direct competition with one another (e.g., using handicapped scoring, different tee boxes, etc.), and still enjoy the golf outing or competition. These factors, together with increased golf programming on television (e.g., golf tournaments, golf news, golf history, and/or other golf programming) and the rise of well known golf superstars, at least in part, have increased golfs popularity in recent years, both in the United States and across the world.
Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” Manufacturers of all types of golf equipment have responded to these demands, and recent years have seen dramatic changes and improvements in golf equipment. For example, a wide range of different golf ball models now are available, with some balls designed to fly farther and straighter, provide higher or flatter trajectory, provide more spin, control, and feel (particularly around the greens), etc.
Being the sole instrument that sets a golf ball in motion during play, the golf club also has been the subject of much technological research and advancement in recent years. For example, the market has seen improvements in golf club heads, shafts, and grips in recent years. Additionally, other technological advancements have been made in an effort to better match the various elements of the golf club and characteristics of a golf ball to a particular user's swing features or characteristics (e.g., club fitting technology, ball launch angle measurement technology, etc.).
Despite the various technological improvements, golf remains a difficult game to play at a high level. For a golf ball to reliably fly straight and in the desired direction, a golf club should meet the golf ball square (or substantially square) to the desired target path. Moreover, the golf club should meet the golf ball at or close to a desired location on the club head face (i.e., on or near a “desired” or “optimal” ball contact location) to reliably fly straight, in the desired direction, and for a desired distance. Off-center hits that deviate from squared contact and/or are located away from the club's desired ball contact location may tend to “twist” the club face when it contacts the ball, thereby sending the ball in the wrong direction, often imparting undesired hook or slice spin, and/or robbing the shot of distance. Accordingly, club head features that can help a user keep the club face square with the ball, such as by reducing twisting, would tend to help the ball fly straighter and truer, in the desired direction, and often with improved and/or more reliable distance.
Various golf club heads have been designed to improve a golfer's accuracy by assisting the golfer in squaring the club head face at impact with a golf ball. When the club face is not square at the point of engagement, the golf ball may fly in an unintended direction, may follow a route that curves left or right, ball flights that are often referred to as “pulls,” “pushes,” “draws,” “fades,” “hooks,” or “slices,” and/or may exhibit more boring or climbing trajectories. The distance and direction of ball flight can also be significantly affected by the spin imparted to the ball by the impact with the club head. Additionally, the spin of the ball can change the behavior of the ball as it rolls and bounces after impact with the ground. Various speeds and directions of spin on the ball can be a product of many factors, including the point of impact, the direction of the club head upon impact, the degree of twisting of the club head upon impact, and the location of the center of gravity of the club head.
The energy and velocity transferred to the ball by a golf club also may be related, at least in part, to the flexibility of the club face at the point of contact, and can be expressed using a measurement called “coefficient of restitution” (or “COR”). The maximum COR for golf club heads is currently limited by the USGA at 0.83. Generally, a club head will have an area of highest COR response relative to other areas of the face, which imparts the greatest energy and velocity to the ball, and this area is typically positioned at or near the geometric center of the face. In one example, the area of highest response may have a COR that is equal to the prevailing USGA limit which is currently 0.83 and may change over time. However, because golf clubs are typically designed to contact the ball at or around the center of the face, off-center hits may result in less energy being transferred to the ball, decreasing the distance of the shot.
The weighting and weight distribution of a golf club head may also influence the energy and velocity transferred to the ball by the impact, as well as the moment of inertia and the center of gravity of the club head. The moment of inertia of the head can be increased, for example, by distributing a greater amount of weight around the perimeter of the head. This, in turn, can reduce the amount of twisting of the club head that occurs on off-center hits, and increase the distance and accuracy of shots on off-center hits. Likewise, the location of the center of gravity of the head can be influenced by the weight distribution of the head. Generally, the desired contact area of the face is aligned with the center of gravity of the head. However, it may be desirable to shift the location of the center of gravity of the head, such as to adjust for common off-center hitting patterns by a golfer, or to produce a certain shot characteristic (e.g., to induce a hook, slice, draw, fade, etc.). Additionally, different clubs having different loft angles can benefit from different weighting, such as a set of iron-type golf clubs having different centers of gravity. For example, a center of gravity that is lower and/or farther backward can produce higher loft and lower spin on the shot, while a center of gravity that is higher and/or farther forward may produce lower loft, greater distance, and higher spin on the shot and/or greater control, each of which may be desirable in certain clubs or for certain golfers. Accordingly, club head features that can permit the weighting and weight distribution of the head to be adjusted or customized may provide improved performance in several ways.
The present device and method are provided to address the problems discussed above and other problems, and to provide advantages and aspects not provided by prior ball striking devices of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.